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angle angular advance axis back pressure bolts brass breadth cast-iron centre circle clearance coefficient of friction compound engine condenser connecting-rod crank position crank-effort crank-pin crank-shaft cross-head curve cut-off valve designed diagram diameter distance distributing-valve draw eccentric eccentric-rods effective pressure equation exhaust exhaust-lap expansion-valve factor of safety feet flange formula friction gear gives greatest Hence high-pressure cylinder high-pressure piston indicator-diagram large cylinder length link-block live steam load low-pressure cylinder low-pressure piston main valve maximum mean effective pressure mean pressure metal moved ordinate packing pipe piston-rod point of cut-off pounds pressure of steam pump ratio of expansion resistance revolutions per minute screw Seaton shaft shown in Fig slide-valve slot small cylinder small piston square inch steam-lap steam-port steel stroke stuffing-box surface surface condenser tensile strength thickness throw triple-expansion engines tube valve-circle valve-stem velocity versin wrought-iron
Page 149 - ... cylinder. Another rule is to make the cylinder ratio equal to the total ratio of expansion multiplied by the fractional part of the stroke completed when cut-off occurs in the high-pressure cylinder.
Page 360 - These elements are — 1. the useful thrust, or ship's true resistance ; 2. the augment of resistance, which is due to the diminution which the action of the propeller creates in the pressure of the water against the stern end of the ship ; 3. the equivalent of the friction of the screw blades in their edgeway motion through the water ; 4. the equivalent of the friction due to the dead weight of -the working parts, piston packings, and the like, which constitute the initial or slow-speed friction...
Page 81 - E direct to the connecting-rod at A, and allowing the centre F to slide in a straight slot. By a just balancing against each other of the errors so produced, and by making the centre F of the lever E, and the centre of the disc K, to coincide at varying points in the travel of the former, a fair motion may...
Page 81 - B nearer to or further from A ; by this means a later point of cut-off may be given to either end of the cylinder at will, and the engine may thus have more steam admitted to one side of the piston than to the other, if required. The same thing may be done for the lead. By altering the position of the crank for which the levercentre F coincides with the centre of the slot J, an increased or a diminished lead may be given.
Page 80 - In that position steam is admitted at each end of the stroke to the amount only of the lead ; and this is done exactly equally on each side of the centre line, the amount of lead being constant for forward and backward motion, and for all degrees of expansion. Thus, when the crank is set at the end of the stroke either way, the centre, F, of the...
Page 79 - M, thereby causing the curved path traversed by the centre F of the lever E to cross the vertical centre line, and •diverge from it on either side at will. The forward or backward motion of the engine is governed by giving the slot this inclined position on one or other side of the vertical centre line ; and the amount of expansion depends on the amount of the inclination, the exactly central or vertical position being
Page 360 - OY (fig. 79), and if we were to draw a line through the intersection parallel to the base, the height which would be thus cut off from the thrust ordinates would represent the deduction to be made from them in respect of constant or initial friction, and the remainders of the ordinates between this new base and the curve would be approximately proportional to the ship's true resistance.
Page 81 - A on the connecting-rod, there would be imparted to the centre F of that lever an unequal vibration above and below the centre of the disc K. The extent of inequality would be twice the versed sine of the arc described by the lower end D of the lever E ; and this would give an unequal port and unequal cut-off for the two ends of the stroke. But this error is corrected by attaching the lower end D of the lever E to the vibrating link B...
Page 391 - LIBRARY GRADUATE SCHOOL OF ENGINEERING HARVARD UNIVERSITY Please sign your name and address on this card, and deposit in box provided. This book may be kept...
Page 79 - ... to the amount of its vibration at the point A ; the centre, F, is for this purpose carried vertically in a slot, J, which is curved to a radius equal to the length of the link, G, connecting the lever, E, to the valve spindle. The slot itself is formed in a disc or sheave, K, which is concentric with the centre, F, of the lever, E, at the moment when that lever is in the position given by the piston being at either end of the cylinder. This...